General Operating Procedures Continued
UsingTwoTraps
TheSRIdualtrapdesigngivesthePurge&Trapusermanyoptionstoeffectivelytrapandreleaseanalytes
fromaparticularadsorbent. Duetoitslowaffinityforwater,Tenax
TM
-GRisespeciallyusefulforthepurgingof
VOCsfromaqueoussamples,making itagoodgeneralpurpose trapforEPAstylepurgeand trap techniques.
TheCarbosieve
TM
packed trap isveryretentive. Because it tends toretaina largewaterpeakandsmear the
otherpeaks, itshouldonlybeusedwhenvinylchloride isamong the targetanalytes. This tendency tosmear
maybereducedbymanipulating thedesorption timesfor the two traps. If theCarbosieve
TM
trap(TRAP2)
isdesorbedwhile theTenax
TM
-GR trap(TRAP1) isstillcold, thecomponentswill refocuson theTenax
TM
-
GR. TheTenax
TM
-GR trap is thenheated todesorb thecomponents inamorenarrowband,whichresults in
sharperpeakson thechromatogram.
INJECTORS
Purge & Trap
Tenax
TM
-GRProperties
CompositeofTenaxTAand30%graphite
Lowwateraffinity
350
o
C temperature limit
200nmaverageporesize
60/80meshsize
Carbosieve
TM
S111Properties
Carbonmolecularsieve
Moderatewateraffinity
400
o
C temperature limit
15-40angstromaverageporesize
60/80meshsize
Available fromAlltech
2051WaukeganRoad
Deerfield, IL60015USA
908-788-5550
Available fromSupelco
SuplecoPark
BellefontePA16823
800-247-6628
Version2.66of thePeakSimplesoftware includes
Epap&t1c.evt
forasingle trap,and
Epap&t2c.evt
for two traps.
